All rights reserved
Page 20 of 33
Function Description
Heat pump compressor
The system is protected with high and low-pressure switches that can stop the compressor and
trigger an alarm.
By heating demand the heat pump compressor starts when the temperature has dropped to set-
point minus the neutral zone. When the compressor is operating the central heating temperature is
raised up to the respective set point before it goes out. The neutral zone helps to avoid frequent
start / stop.
Frequency-controlled compressor (variable capacity)
The frequency is controlled by a PI regulator. The PI regulator parameters are set in the HEATING
PUMP menu.
OTo avoid frequent ON / OFF couplings on the compressor because of the large hysteresis on
central heating temperature, the compressor starts only when the PI controller's capacity reaches
above 40%. The compressor stops when PI regulator capacity falls to under 10 %.
If the compressor continues to start/stop at short intervals, it may be necessary to set a wider neu-
tral zone (in the CENTRAL HEAT / NEUTRAL ZONE Menu).
Ground pipe and brine
The brine pump always runs with the compressor and starts 1 minute before and runs 1 minute
longer. After a week of inactivity, the pump starts briefly to prevent blockage.
The environmental pressure switch triggers an alarm and stops the system if there is a leak in the
brine system.
Condenser and heating circulation pump
The system has a water-cooled condenser with a circulation pump.
To prevent excessive condenser pressure in the event of failure of the high pressure switch, hot
water is circulated in the central heating system until the temperature falls below the set maximum
value for the compressor, before the compressor is started.
After a week of inactivity, there is a brief periodic test run.
In addition the pump has the following operating modes, which depend on the overriding control
mode:
-
Winter operation:
The pump runs constantly.
-
Summer operation: The pump is inactive (except for brief periodic test run).
